1879.] on the Story of the November Meteors. 41 



and tlic resistance to wliicli tlicy become then suddenly exposed must 

 raise tlicin to a temperature wliicli exceeds that of the most intense 

 furnace. The heat is enough first to melt and then to dissipate in 

 vapour the most refractory substances, and it only now and tlien 

 happens that even a part of a meteor escapes this fate, and reaches 

 the ground. They are for the most part lost in vapour ere they get 

 within several miles of us. The difficulty, indeed, is not to account 

 for their incandescence, but to see why they do not emit a greater 

 flood of light where the heat must be so intense. And, in fact, they 

 cannot be other than very small bodies, or they would be much 

 brighter. The average weight of those visible to the unassisted eye 

 appears to be under an ounce, and the telescopic ones, of course, are 

 much lijTfhter. 



SPORADIC METEORS, AND METEORIC SHOWERS. 



Meteors may be distributed into two very obvious classes — casual 

 meteors, which dart irregularly through the sky, and meteoric showers, 

 which stream into our atmosphere in one definite direction, and at 

 stated intervals of time. We are concerned at present with the meteoric 

 showers. Many such are known to exist, of which the j^rincipal are 

 the August shower, through which the earth j)fisses every year upon 

 the 9th, 10th, and 11th of August; and the great November shower, 

 which is discharged ujDon the earth three times in a century. The 

 November meteors are those about which most is known, and it was 

 of these, therefore, that the lecture chiefly treated. 



THE REGIONS FROM WHICH METEORS COME. 



To make their history intelligible, it was necessary to explore, in 

 some degree, the regions from which they come. For this purpose a 

 great diagram was exhibited on a scale rather more than thirty times 

 the scale of the accompanying woodcut. Yet, though the diagram was 

 so large, every hundredth of an inch uj^on it represented a distance iii 

 nature equal to the interval between the earth and the moon. The 

 distance from the earth to the sun on this diagram was a decimeter, 

 that is, four inches; and, on the same scale, the nearest fixed star 

 would have to be placed at a distance of twenty kilometers, or upwards 

 of twelve miles. 



ORBIT OF THE GREAT NOVEMBER SWARM. 



In these vast celestial spaces, there are no rails over the rough- 

 nesses of which the train must be made to rattle, if it is to move at all ; 

 there are no wheels to be worn out ; there is no air in which a wind 

 must be produced, or through which noise will be propagated. The 

 music of the spheres is not a sound audible to the ear, and an impedi- 

 ment to motion : it is harmless, it is altogether good, it is the pleasure 



